Only sure fire way to force Trump to go 3rd party (which he can afford to do) is for the 14 candidates (except Cruz) to keep attacking Trump by name.
In other words if GOP elites force him out of GOP, would you blame Trump to go 3rd party? What ever happened to accept defeat in poll numbers graciously?
Are the professional politicians gone postal because a non-professional politician has leap frogged them in poll numbers?
But, if the establishment forces him out but not Cruz, and Cruz is the nominee, would Trump run 3rd party?